Gear grinder



Patented May 3, 1927.

UNITED STATES PATENT OFFICE.

MAX HAAG, OF SCHWAMENDINGEN, SWITZERLAND, ASSIGNOR TO MAAG GEAR WHEEL AND MACHINE COMPANY LTD., F ZURICH, SWITZERLAND, A CORPORATION 0F SWITZERLAND.

'om GBINDER.

Application -led November 30, 192.3.' SerialNo. 677,641.

trolling. the movements of the gear blank relative toan'abrasive wheel or Wheels.

" It is an object of the present invention to provide improved means for rapidly actuating and indexing a work blank so that the tooth curves of gears may be rapidly formed -1 'upon a generative principle.

, One feature which enables me to accom plish the. above named object. is that I provide means for reciprocating a Work spindle through a'distance equal to or greater than that during which the teeth being operated on are engaged by the surfaces of the wheels. Another feature which is advantageous is that this distance also is made an exact multiple of the circular pitch of the gear. To effect the indexing movements of the gear,

the work spindle is moved in a direction nor-- mal to the direction of rolling movement to disengage4 the blank from the wheel or r 4Wheels and then returned to the initial position without rolling action. The blank is at that point again caused to engage the wheel or Wheels and the operation continued.

By these means, successive teeth are'brought into engagement with the abrading means until the entire gear is acted upon by the` Wheels. Simultaneously with the reciprocatory motion of the blank while in engagement with the abrasive wheel or Wheels it is r rotated upon its axis by means presently to be'described. A

Preferably I mount the gear blank on a spindle at the outer end of a pair of freely swinging` arms .similar to those disclosed 1n the application of Tanner and Knowles` Serial No. 621,307 filed February' 26, 1922, and provide a ixed precision rack substantially` under the gear engaging portions of the abrasive Wheels.` On the Work spindle is a master-gear of the same pitch diameter and preferably having the same number of teeth as thegear blank being ground. A spring is provided which serves to hold this master gear in engagement with the rack and an eccentric,y or other form of cam, serves to periodically withdraw the master gear and blank from the precision rack and wheels respectively in timed relation to the rolling movements of the blank.

.In gears of usual or coiiventional form, the Contact line varies from about 1.2 to about 3.2; that is, al gear tooth is in contact with the tooth of a mating gear While the gears rotate'a distance represented by from 1.2 to 3.2 times their circular pitch., The operative surfaces of the Wheels represent oppo- .site flanks of the same or adjacent teeth of a tixed'rack and the gearfbeing formed is rolled past it. The distance through which the gear is rolled past the Wheel or Wheels in vthe preferred form of the present invention is a multiple of the circular pitch and more than -a distance equal to the contact line.` For this purpose, I provide means to adjust the amount of rolling movement given to the gear blank.

lVitli these and other objects in view, my

invention consists in the features of Construction and operationv set forth in the following specification and illustrated in the accompanying drawing.

In the accompanying drawing, I have shown my invention embodied in a single purpose spur gear grinding machine but it will be understood that the invention can be otherwise embodied and that the drawing is not to be Iconstrued as defining or limiting the scope of the invention, the claims appended to this specification being relied upon for that purpose.

In the drawing:

Figure l is aplan view' of the principal parts of a grinding machine made according to the present invention.

Fig. 2 is afront elevation partly in section.

Fig. 3 is a detail view of the spindle and means'for4 rolling the gear blank taken on line 3-3 of Fig. 2.

Fig. 4V is a diagrammatic view showing the movements of the Work spindle axis.

In the above mentioned drawing, I have shown but one embodiment of the invention which is now deemedpreferable but it is to be understood that changes and modifications may be made within the scope of the appended claims without departing from the spirit of the invention.

Briefly, my invention in its broadest asv peet comprises the following principal parts: first, a base having a column and swinging arms supported thereon; second, a work spindle rotatably mounted at the free end of the swinging arms; third, means to oscillate one of the arms to actuate the work spindle; fourth, abrasive naeans adtoward the precision rack during its rolling movement; and seventh, means to positively withdraw-'the work spindle so that the master gear and blank will be out of contact with the rack and wheels respective- 1y during its non-rotative motions.

Rfeerring more in particular to the figures of the drawing, I provide a base 10 having a column 11 mounted near one side thereof on which are mounted freely swinging frames or arms 12 and 13. These arms 12 and 13 are, or may be, subsantially identical with the swinging arms disclosed in the above mentioned copending application. Mounted upon the router one of these arms 13 is a vertical spindle 14 rotatably mounted and carrying a master gear 15 and providing supporting and rotating means for the work supporting arbor 16.

On the upper horizontal surface of the base 10 are disposed the supports 17 for the abrasive wheels 18, two of which are preterably provided. These wheels 18 are mounted upon rotatable spindles 19 provided within supporting heads 20 which can be adjusted to position the abrasive wheels 18 in proper osition relative to the blank being operate upon. As the construction of these wheel supporting heads 2O and their supports 17 1s substantially similar to those described in the above mentioned copending application, further description is thought to be unnecessary.

Fixed to a portion of the base 10 preterably in a manner permitting it to be readily removed so that others may be substituted is a precision rack 21. rll`his is adapted to be engaged by the master gear 15 mounted upon the lower end of the work supporting spindle 14 and rotating therewith. Below the master gear 15 is a roller bearing 23 adapted to engage a plane surface 24 par- 4 allel to and adjacent the pitch plane oi the rack 2l so that the Work spindle 14 is held from movement beyond a critical position in one direction. .l

lin order to actuate the swinging arms 12 and 13 to properly move the work spindle 14 and the blank thereon relative to the abrasive wheels 18, l provide a crank 25, the stroke of which may be adjusted by means of the diametral slot as shown., Flhis crank 25, which may be rotated at any sired speed by its driving shalt 26 through the gearing shown, is connected by means ot suitable rod 27 to one ot the swinging arms l2. Rotation ot this crank 25 will therefore oscillate one of the swinging arms 12 and reciprocate the other one 13. A spring 28 attached to a part of the outer larm 13 ser-ves to normally force it in the direction of the abrasive wheels 18. l/Vith the work spindle'14 in this position, the gear blank engages the radial surfaces of the abrasive wheel 18 and the master gear 15 on the spindle 14 is held in engagement with the precision rack-21. Movement therefore of the arm 12 in one direction will cause the Work spindle 14-to be rotated by reason of the engagement oit' the master gear 15 with the rack 21 so that a rolling action of a gear along a rack is simulated. The distance through which the blank is rolled in this direction is sufficient to cause the wheels 18 to engage the entire contour of the gear teeth in contact therewith and, in order to avoid the necessity of complicated indexlng mechanisms, thisi distance is made an exact multiple of the circular pitch of the' gear. As the master gear 15 corresponds to the gear blank being ground, its rolling circle equals the pitch diameter of the blank.

Mounted to rotate in timed relation with the crank 25 is a cam or eccentric 30 which may be driven by means of the connections including a Worm and worm gear 32 most clearly shown in Fig. 2. This eccentric 0r cam 30 is so timed that as soon as the gear blank has completed its rolling movement in one direction, the freely swinging arm 13 carrying the spindle 14 is oscillated about its pivoted joint to disengage the master gear 15 from the rack 21 and the arm 12 and spindle 14 are held with the master gear 15 out ofcontact with its rack 21 while the crank 25 returns the work spindle 14 and arm 12 to its initial position, at which time the eccentric or cam 30 permits the master gear 15 to again be resiliently forced toward the rack 21 under the influence of the spring 28. As soon as the master gear 15 reengages the rack 21, the crank 25 again moves the spindle 14 in order to again roll the blank in contact with the wheels 18.

As the distance through which the work blank is rolled equals an enact multiple of the circular pitch of the gear being formed and the backward movement takes place while the master gear 15 and rack 21 are out of engagement and conquently no rotative movement ot' the spindle 14 occurs, the effect is to index the spindle 14 lor the neat rolling movement oft the blank. The work spindle 14 will therefore be indexed with each successive rolling movement of the blank. Also the number ot circular pitches through which the work blank is rolled is l chosen to be incommensurate with the nurnber ot teeth in the gear so that after the hlankxhas completed one rotative movement, successive rotative movements will engage .different teeth with the wheels and in this lou (itl

way all of the teeth of the blank will be engaged.

To prevent any accidental rotative movement of the work spindle 14 and gear blank during their return movement, a brake may be provided on the spindle. This as shown comprises a band 35 surrounding a portion of the work spindle 14 so that a slight and adjustable amount of friction between the band and part of the spindle maybe provided by proper adjustment of the band 35.

vThe path of movement of the spindle 14 is indicated in Fig. 4. In one direction during which the blank is rolled and the master gear 15 engages the rack 21, this movement is in a straight line. The return movement of the spindle 14 is substantially `the curved path as indicated. This motion is sufficient to entirely disengage the blank from the wheels 18 and the master gear 15 from the rack 2-1 so that the return movement may take place without any rolling or rotative movement of the blank and spindle 14.

The above described mechanism is adapted to withdraw the wheels 18 after each rolling movement in one direction. In this case during each movement of the spindle 14 in one direction, the blank is rolled and with each movement in the opposite direction the f spindle is moved without rotation to return the blank to its initial osition. This is by reason of the cam eing rotated at the same speed as the crank 25.

If it is desired to ive the blank additional rolling movements etween theV return nonrotative or indexing movements, itis only necessary to. change the timing of the cam 30, the shapebeing slightly modified also. This timed relation between the cam 30 and crank 25 may be 1:3, 1:5 orso forth. With the cam timed to make one revolution while the crank makes three or five revolutions the blank is rolled past the wheels three or five times after which the blank is returned -without rolling to index it.

What I claim is:

1. The method of grindingtooth curves of gears comprising supporting a gear so that it may be move in any direction while its axis is maintained in parallel ositions, rolll ing said gear blank past an a rasive wheel, returning the blank to its .initial position without further rolling movements, and moving said blank into and out of relation with said wheel in timed relation with the rolling movements. y

2. The method of grinding tooth curves of gears comprising rolling a gear blank past an abrasive wheel, returning the blank toits initial position without further rolling.

movements, .said blank being maintained in operative relation with said wheel while it is being rolled past said wheel, and moved out of engagement therewith during its return movement.

3. The method of grinding tooth curves of gears comprising rolling a gear blank past an abrasive wheel a distance .equal to a multiple of the circular pitch of saidy gear blank, disengaging said blank from said engaged by said wheel.

v4f. The method of grinding tooth curves of gears comprising rollin a geark blank past a pair of oppositely disposed abrasive wheels while its axis is maintained in parallel positions. the distance rolled being suicent to cause said wheels to engage the com plete profiles of said' tooth curves, indexing said blanks while out of 'contact with said wheels, and alternating said rolling and indexing movements untll the tooth curves are completely formed.

5. The method of rinding tooth curves of gears comprising rolling agear blank on a spindle along a fixed rack, said spindle hav ing a master gear thereon and the circle upon which said blank is rolled having a diameter equal to the pitch diameter of the gear blank, the rolling motion taking place past a pair of oppositely disposed abrasive wheels and the distance rolled being sufficient to cause said wheels to engage the complete profiles of said tooth curves, indexing said blanks while out of contact-with said wheels, and alternating said rolling and. indexing movements until the tooth. curves are completely formed.

6. A gear tooth grinder comprising in combination, a base', an abrasive wheel adjustablyA mounted thereon, a work spindle mounted for movement in any direction f'while its-'axis is maintained always in parallel positions,'.means to effect a rolling motion in one direction of a blank. on said spindle as it passes the abrasive wheel, means to return said spindle to its initial position without rotation, and means to engage and disenga e said blank with said wheel in timed reation to the rolling movements 'of the blank. 7. Al gear tooth grinder comprising in combination, a base, an abrasive wheel adjustably mounted thereon. a. work spindle` mounted ,for movement in any direction while its axii'l is maintained alwa sin parallel positions, means to effect a rol ing motion in one direction of a blank on said spindle upon a circle equal to its itch diameter as it passes the abrasive whee means to return said spindle to its initial position without rotation, and means to engage said blank with said wheel during its rolling motion and to disengage it therefrom during its return m tii`n ar tooth grinder comprisin in justably mounted thereon, a v"orlr spindle mounted for movement in any direction While its axis is maintained always in parallel positions, means to eie'ct a rolling motion in one direction or" a blank on said spindle as it passes the abrasive Wheels, means to return said spindle to its initial position without rotation, means to engage said blank with said wheel during the rolling movements of the blank, and means to positively disengage it therefrom during its return motion.

9. A. gear tooth grinder comprisin in combination, a base, an abrasive vvhee adjuslably mounted thereon, a Work spindle mounted for movement in any,7 direction while its axis is maintained always in parallel positions, a gear blank thereon, a fixed rack on said base, a master gear on said spindle, means to eiect a rolling motion of said blank in one direction as it passes the abrasive wheel, means to return said spindle to its initial position without rotation, and means to engage and disengage said blank with said Wheel in timed relation to the rolling movements of the blankt 10. A. gear tooth grinder comprising in combination, a base, an abrasive wheel adjustably mounted thereon, a work spindle mounted for movement in any direction while its axis is maintained always in paral# lel positions, a gear blank thereon, a ixed rack on said base, a master gear on said spindle, means to move said spindle to effect a rolling motion of said blank in one direction as it passes the abrasive Wheels, means to return said spindle to its initial position without rotation, and means to engage and disengage said blank with said wheel alternately in timed relation to the rolling and return movements of the blank.

l1. A gear tooth grinder comprising in combination, a base, an abrasive Wheel adjustably mounted thereon, a Work spindle mounted for movement in any direction while its axis is maintained always in parallel positions, a gear blank thereon, a fixed rack on said base, a master gear on said spindle, means to engage said master gear with said rack while said spindle is bein moved to 'effect a rolling motion of the blan in one direction as it passes the abrasive Wheel, means to return said spindle to its initial po sition, means preventing rotation of said spindle during its return movement, and means to engage and-disengage said blank with said Wheel in timed relation to the roll ing and return movements of the blank.

:in testimony whereof, I hereto ax my signature. 

